The placement of cotton floss ligatures in a position apical to the gingival margin of premolars and molars in young dogs induced an acute inflammatory reaction in the periodontal tissues resulting in loss of connective tissue attachment and alveolar bone. 2. Bone resorption could be observed histologically within 7 days, and radiographically within 2 to 3 weeks after ligature placement. 3. Daily administration of indomethacin interfered with the periodontal tissue response to ligature placement. Indomethacin was shown to (i) delay the onset and to suppress the magnitude of the acute inflammatory reaction, and (ii) decrease the degree of alveolar bone resorption.
